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轴流式风力灭火机的轴流叶轮气动性能研究
Study on Aerodynamic Performance of Axial-flow Impeller for Axial-flow Pneumatic Extinguisher
【作者】 禇双磊；
【导师】 俞国胜；
【作者基本信息】 北京林业大学 ， 机械设计及理论， 2010， 博士
【摘要】 轴流式风力灭火机是一种不同于现有离心式风力灭火机的新型便携式风力灭火机,其轴流叶轮是轴流式风力灭火机的核心灭火部件。因此,轴流叶轮气动性能的好坏直接关系到轴流式风力灭火机的灭火性能。本研究主要是针对轴流式风力灭火机中轴流叶轮的气动性能进行试验研究和CFD数值模拟,为设计高效率的轴流式风力灭火机提供理论依据。本研究的主要内容和结论如下：1.根据国家标准GB／T 10280-1999《便携式风力灭火机技术条件》规定的便携式风力灭火机中灭火风机性能要求(出口风量)和将来的新型轴流式风力灭火机的设计设想,设计制造了轴流式灭火风机气动性能试验装置。该试验装置可以模拟在实验室条件下轴流叶轮高速旋转驱动空气自由流动的状态。并通过更换锥形射流风筒来验证轴流叶轮在轴流风机和轴流式灭火风机的气动性能。2.通过对不同叶片数(5、6、7)和叶片角度(30°、34°、38°)的5种轴流叶轮构成的轴流风机进行气动性能试验,试验结果表明轴流叶轮叶片数为6、叶片角度为38°的轴流风机风量最接近设计要求,达到1406.1m3／h,全压为438.35Pa,功率为0.501kw,效率为34.15%,基本满足灭火风机的气动性能要求,并且轴功率远小于便携式风力灭火机的功率3.轴流风机内部流场的数值模拟结果表明：轴流叶轮叶片数Z=6,叶片角度为38°的5号轴流风机叶轮外缘速度较大,轮毂出口端低速区面积较小,叶身出口速度较大,旋转推力较大,与气动性能试验结果一致。4.将锥形射流风筒安装在轴流风机上形成轴流式灭火风机后,通过对不同叶片数(5、6、7)和叶片角度(30°、34°、38°)的5种轴流叶轮构成的轴流式灭火风机整机进行气动性能试验,试验结果表明轴流叶轮叶片数为6、叶片角度为38°的5号轴流式灭火风机风量最接近设计风量,达到1400.3m3／h,全压为584.61Pa,功率为0.45 kw,全压效率稍微偏低为50.44%,气动性能良好,基本满足灭火风机的气动性能要求,并且轴功率远小于便携式风力灭火机的功率要求；因此应用于轴流式风力灭火机的轴流叶轮叶片数宜取6片,叶片角度宜取38°5.轴流式灭火风机内部流场的数值模拟结果表明：与轴流风机相比,轴流式灭火风机中的锥形射流风筒的作用就是提高风速,加速空气射流的形成。其中轴流叶轮叶片数Z=6,叶片角度为38°的5号轴流式灭火风机轮毂出气端回流区面积较小,功率消耗较少。锥形射流风筒内部速度矢量较大,分布较密集,射流出口速度较大,风量较大,与气动性能试验结果基本一致。
【Abstract】 Axial-flow pneumatic extinguisher is a kind of new portable extinguishers and is different from the existing centrifugal pneumatic extinguisher. Axial-flow impeller is a core fire-fighting components of axial-flow pneumatic extinguisher. Therefore, the aerodynamic performance of axial-flow impeller will have a direct effect on the fire-fighting performance of axial-flow pneumatic extinguisher. This study is mainly aimed at experimental study and CFD numerical simulation of axial-flow impeller’s aerodynamic performance about axial-flow pneumatic extinguisher and the results provide a theoretical basis for the design of high-efficiency axial-flow pneumatic extinguisher.Main contents and conclusions are as follows:1.According to fire-fighting fan performance requirements provided by the national standard GB/T 10280-1999《portable pneumatic extinguishers-technical specification》such as outlet flow volume, and considering the design idea of future axial-flow pneumatic extinguisher, the axial-flow fire-fighting fan aerodynamic performance test device was designed and manufactured. The free flow of driven air about high-speed rotating axial-flow impeller of the test device under laboratory conditions can be simulated. Axial-flow fire-fighting fan aerodynamic performance test device verifies aerodynamic performance of axial-flow impeller in the axial-flow fan and axial-flow fire-fighting fan respectively through the removable cone-shaped jet duct.2.The aerodynamic performance tests for axial-flow fan composed of the number of different leaves (Z=5,6,7) and blade angle (30°、34°、38°) of axial-flow impeller were carried out. The experimental results indicated that:When the blade angle of axial-flow impeller is 38°, the flow volume of No.5 axial-flow fan which the blade number Z=6 is 1406.1m3/h,closest to the design requirements, total pressure is 438.35Pa, power is 0.501kw, total pressure efficiency is 34.15%,basically meets the aerodynamic performance requirements of fire-fighting fan, and shaft power is much smaller than that of a portable pneumatic extinguisher.3. Numerical simulation results of axial-flow fan internal flow field showed that:when the blade angle of axial impeller is 38°, the outer edge speed of No.5 axial-flow fan which the blade number Z=6 is greater, low-speed area of hub outlet is smaller, outlet velocity of blade body is larger, rotation thrust is greater, numerical simulation results are consistent with aerodynamic performance test results.4.Axial-flow fire-fighting fan was formed after the cone-shaped jet duct was installed in the axial-flow fan, the aerodynamic performance tests for axial-flow fire-fighting fan composed of the number of different leaves (Z=5,6,7) and blade angle (30°、34°、38°) of axial-flow impeller were carried out. The experimental results indicated that:When the blade angle of axial-flow impeller is 38°, the flow volume of No.5 axial-flow fire-fighting fan which the blade number Z=6 is 1400.3m3/h,closest to the design flow volume, total pressure is 584.61Pa, power is 0.45kw, total pressure efficiency is 50.44%, integrated aerodynamic performance is well, basically meets the aerodynamic performance requirements of fire-fighting fan, and shaft power is much smaller than that of a portable pneumatic extinguisher. Therefore, the optimum blade angle of axial-flow impeller which is applied in the axial-flow fire-fighting fan is 38°, the optimum blade number is 6.5. Numerical simulation results of axial-flow fire-fighting fan internal flow field showed that: compared with the axial-flow fan, the function of conical jet duct in the axial-flow fire-fighting fan is to improve the speed and accelerate the formation of the air jet. When the blade angle of axial impeller is 38°, the flow volume of No.5 axial-flow fire-fighting fan which the blade number Z=6 is greater, refluence area of hub outlet is smaller, power consumption is lower. The internal velocity vector of conical jet duct is larger, distributed intensively, jet outlet velocity is higher, numerical simulation results are consistent with aerodynamic performance test results.